System of electrical distribution.



- f No. 7'|4,ll8. Patented Nov. l8, I902.

M. 0. TROY.

SYSTEM [IF ELECTRICAL DISTRIBUTION.

(Application filed Apr. 8, 1902.) (No Model.)

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UNITE S'TnTns PATENT OFFICE,

MATTHEWV O. TROY, OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK.

SYSTEM OF ELECTRICAL DISTRIBUTION.

SPECIFICATION forming part of Letters Patent No. 714 118, dated November18, 1902.

Original application filed December 19,1901, Serial No. 86,473. Dividedand this application filed April 3, 1902. Serial No. 101,180. (Nomodel.)

To (LU "1071,0772, it may concern.-

Be it known thatI, MATTHEW O. TROY, a citizen of the United States,residing at Lynn, county of Essex, State of Massachusetts, have inventedcertain new and useful Improvements in Systems of ElectricalDistribution, (Case No. 2,811, division of my prior application, SerialNo. 86,473, filed December 19,

1901,) of which the following is a specification.

My present invention relates more especially to an arrangement orarrangments whereby a circuit carrying a variable load may be suppliedautomatically with substantially constant current derived from aconstant-potential source.

The invention is intended more particularly for use in those cases wherethe translating devices supplied with constant current possessself-induction inherently or may be accompanied by adjunctive devicespossessing inductance.

Generally speaking, my invention consists in connecting in circuit withthe translating devices a reactance of different sign from the reactancepresent in the translating devices themselves. When, therefore,translating devices are cut into circuit, their resistance tends toincrease the total impedance, while their reactance by counterbalancinga corresponding portion of the permanentlyincluded reactance of oppositesign serves to maintain the resulting impedance of the circuitsubstantially constant. If translating devices are cut out of circuit,the reduction in impedance which would otherwise take place is similarlyprevented by the fact that a portion of the permanently-connectedimpedance is no longer balanced in its effect by the reactance of thetranslating devices thus cut out. The circuit being of substantiallyconstant impedance regardless of load therefore carries a substantiallyconstant current.

The novel features which I believe characterize my invention I have setforth with particularity in the appended claims. For a description,however, of embodiments of my invention and of their modes of operationreference is to be had to the following specification, taken inconnection with the accompanying drawings, in which- Figures 1 and 2 arediagrams of modified forms of my invention, and Fig. 3 a diagram of astill different form.

In Fig. 1 a source of constant-potential alternating current isindicated at 1, and mains 2 3 extend therefrom, from which translatingdevices of any suitable character may receive current. Connected acrossthese mains is a circuit at, arranged in accordance with my invention tobe supplied with substantially constant current. This circuit is shownas supplying current to a series of arclamps 5 to 9, inclusive. Theselamps are represented as of the differential typethat is,

each one is provided with a series coil, such as 10, for striking thearc, and a shunt-coil, such as 11, for opposing the action of the series coil, and thereby regulating the length of the arc.Short-circuiting switches, such as 12, serve to cut the lamps into orout of circuit, as desired.

In series with the constant-current circuit I permanently connect acondenser 13 or other device having the effect of capacity. Such devicesare well known in the art and require no description here. The capacityof the condenser may be chosen so that when all the lamps or othertranslating devices are out of circuit current of the required valuewill flow. When new one of the lamps is cut into circuit by opening itsshortcircuiting switch, the inductance of the lamp balances a portion ofthe reactance of the condenser. The total impedance of the lamp and thecondensertherefore remain approximately the same as the impedance of thecondenser alone. Further increase in the number of lamps in circuit hasa substantially similar effect. The result is the maintenance of anearly constant current in the circuit 4- regardless of the number oflainps or other translating devices in circuit. It is not claimed,however, that the current in the circuit 4 is absolutely constant, sincesuch is not the fact. In general the current ishigher for medium loadsthan for either small or large loads. As the current in the circuit 4 isto a greater or less extent a leading current, a beneficial effect uponthe system as a whole may be obtained when this constantcurrent circuitis operated in conjunction with other circuits or translating devicestaking a lagging current. The power factor of the system as a Whole isthereby improved. At 14 I have represented aconstant-current circuit fedfrom the mains 2 3 by a constantcurrent transformer of well-known type.This transformer takes a variable lagging current from the mains, whichlagging current is to a greater or less extent counterbalanced by theleading current taken from the mains by the circuit 4.

In case the translating devices to be supplied With constant current donot of themselves contain inductance they may each be provided with anadjunctive device possessing inductancesnch, for example, as aninductance-coil. Each translating device and its correspondinginductance-coil may therefore be cut into or out of circuit simultaneously and will produce the same regulating effect in the circuit asWould be the case with arc-lamps, which are inherently inductive. Thearrangement thus outlined is shown in Fig. 2 and will be seen to consistof a constant-current circuit 15, including the regulating-condenser 16and a series of inductance-coils and incandescent lamps, one of theinductance-coils being indicated at 1'7 and the lamp correspondingthereto at 18. A short-circuiting switch for each lamp and itsinductance-coil is employed for cutting the lamp and coil into or out ofcircuit. One of these switches is indicated at 19 in operative relationto the inductance-coil 17 and lamp 18. Cutting in or out a lamp and itscorresponding inductance-coil has the same regulating action set forthin' connection with the arc-lamps shown in Fig. 1.

It may be found in practice that the regulating-condenser has the effectof accentuating the higher harmonics in the current sup plied, therebyseriously interfering with the regulating action of the system. In suchcases the condenser may be considered as offering more or lessopposition to the passage of waves of the fundamental frequency and butlittle opposition to the passage of waves of higher frequency. Toobviate this defect, I insert in series with a constant-current circuitan inductance-coil or other device possessing self-induction. Thisinductance-coil is represented at 20 in Fig. 3, which figure representsa system substantially the same as those shown in Figs. 1 and 2, butdiffering therefrom in the minor particular that the constant-currentcircuit 21 is supplied from the constant-potential source 22 through atransformer 23. In order that the inductancecoil 20, inserted in theconstant-current circuit for the purpose of suppressing higherharmonics, may not have the effect of impairing the regulation of thesystem, I increase the amount of regulating-condenser 24 sufiiciently tobalance the lagging component of current due to the inductance-coil 20.The system as thus arranged is substantially free from magnifiedharmonics and regulates for approximately constant current in the manneralready described. As in the case shown in Fig. 1, the constant-currentcircuit in Fig. 3 is represented as supplying translating devices in theform of arc-lamps 25.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. The combination ofa source of constantpotential current, acomsumption-circuitconnected thereto, translating devices possessinginductance adapted to be connected in series in said circuit or cut outof said circuit, and a device possessing the eifect of capacityconnected permanently in said circuit.

2. The combination of a source of constantpotential current, a seriescircuit supplied thereby, transmitting devices possessing reactance ofone sign adapted to be cut into or out of said circuit, and a devicepossessing reactance of the opposite sign connected permanently in saidcircuit.

3. The combination of constant-potential leads, a series circuitconnected to said leads, a device possessing the effect of capacityconnected in said circuit, and devices possessing the effects ofinductance and resistance adapted to be cut into or out of said circuit.

t. The combination of a source of alternating current of constantpotential, a series circuit fed thereby, arc-lampsin said circuit, adevice possessing capacity also in said circuit, and an inductivecircuit also fed from said source.

5. The combination of a series circuit including translating devicespossessing inductance, means for impressing on said circuit analternating electromotive force of substantially constant value, andmeans for maintaining a constant current in said circuit consisting of adevice in said circuit having a sufficiently large capacity effect tocause a leading current to flow in said circuit.

6. The combination of a series circuit containing translating devicespossessing inductance, means for impressing on said circuit analternating electromotive force of substantially constant potential, anda condenser connected in said circuit and of such value that as thenumber of translating devices is varied the increase or decrease in thenet reactance of the circuit approximately balances the decrease orincrease of resistance, whereby the total impedance remainssubstantially constant.

In witness whereof I have hereunto set my hand this 31st day of March,1902.

MATTHEW O. TROY.

WVitnesses:

DUGALD MoK. MoKILLoP, JOHN A. McMANUs.

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